Abstract

The accurate calculation of doses during external radiotherapy sessions is necessary. Recently,the models used for this purpose have been the point kernel, pencil‑beam, and collapsedcone superposition/convolution combination models. In this study, it is aimed to determinepoint/pencil‑beam kernels to be used in dose calculations. For this purpose, tallying pencil‑beamﬂuence based on Monte Carlo (MC) simulations is investigated by scoring a volume of interestcentered in a cubic water phantom at a depth of 10 cm and the irradiated feld of 10 cm × 10 cm.The ﬂuence is calculated for each mono‑energetic photon ranging from 0.25–6 MV at incrementsof 250 keV. The output of the four ﬂuence kernels along the depth Z around the central axis iscategorized for both the primary and secondary photons and electrons. Here, a database forpencil‑beam kernels is established for each category. For validation purposes, other MC simulationsare carried out for ﬂuence calculations as produced by the predetermined poly‑energetic spectra for aVarian 6 MV linear accelerator. The net results show a good ft of the two convoluted ﬂuence spectraquantities for both mono‑energetic and poly‑energetics‑based simulations except little singular peaks.